The following U.S. patents are incorporated herein by reference:
U.S. Pat. No. 6,350,165 discloses an inboard/outboard powered watercraft that incorporates a transmission in its vertical drive unit for providing two forward speeds plus reverse. The transmission is packaged to fit within the vertical drive unit by incorporating a bevel gear apparatus. In one embodiment, the transmission also includes a planetary gear apparatus together with two hydraulic clutches and a ring gear brake. In a second embodiment, three hydraulic clutches are utilized with bevel gears alone to provide the two forward and reverse speeds.
U.S. Pat. No. 6,435,923 discloses a two-speed transmission with reverse gearing for a watercraft. The transmission is disposed in the gimbal housing passing through the transom of the watercraft. A pair of planetary gears share a common ring gear to provide both forward-reverse and first-second gearing in a very compact package. The transmission housing may be formed in two portions, a first housing containing the forward-reverse gear mechanisms and a second housing containing the first-second gear mechanism. The transmission output shaft is connected to the drive shaft of a vertical drive unit by a double universal joint that may be replaced without disassembling the transmission components.
U.S. Pat. No. 7,891,263 discloses a two speed transmission system mounted for driving a marine craft comprising: an input shaft coupled in direct connection with a driveshaft of an engine of the marine craft; an output shaft coaxial with the input shaft coupled in direct connection with a driveline of the marine craft; a first gear train for transmitting drive at a fixed first gear ratio; a second gear train for transmitting drive at a fixed second gear ratio; a first friction clutch operable to engage/disengage the first gear train; and a second friction clutch operable to engage/disengage the second gear train, wherein in shifting between the first gear ratio and the second gear ratio one of the friction clutches is disengaged using controlled slippage while the other friction clutch is engaged using controlled slippage.
U.S. Pat. No. 7,942,712 discloses an outboard motor that includes a power source, a boat propulsion section, a shift position switching mechanism, a clutch actuator, and a control device. The shift position switching mechanism switches among a first shift position in which a first clutch is engaged and a second clutch is disengaged, a second shift position in which the first clutch is disengaged and the second clutch is engaged, and a neutral position in which both the first clutch and the second clutch are disengaged. When a gear shift is to be made from the first shift position to the second shift position, the control section causes the clutch actuator to gradually increase an engagement force of the second clutch. The outboard motor reduces the load to be applied to the power source and the power transmission mechanism at the time of a gear shift in a boat propulsion system including an electronically controlled shift mechanism.
U.S. Pat. No. 8,109,800 discloses a transmission device that includes hydraulic type transmission mechanisms arranged to change the speed or the direction of rotation of an engine, and hydraulic pressure control valves arranged to control hydraulic pressure supplied to the hydraulic type transmission mechanisms. The hydraulic pressure control valves are disposed on one side or the other side in the watercraft width direction. The transmission device provides an outboard motor capable of securing cooling characteristics of a hydraulic pressure control valve without incurring complexity in structure and increase in cost.
U.S. Pat. No. 8,157,694 discloses an outboard motor having a power transmission mechanism for transmitting power of an engine to a propeller. The power transmission mechanism has a transmission ratio changing unit having a planetary gear train including a sun gear, planetary gears, and an internal gear. The internal gear is connected to an input side shaft on the engine side. The planetary gears are connected to an output side shaft on the propeller side. The sun gear is connected to a stationary portion via a one-way clutch. The planetary gears and the internal gear and/or the sun gear are connected by an on-off clutch. When the on-off clutch is disengaged, the one-way clutch is engaged and the speed from the input side shaft is outputted from the output side shaft with a reduced speed. When the on-off clutch is engaged, the speed from the input side shaft is outputted from the output side shaft with the same speed.
U.S. Pat. No. 8,277,270 discloses a boat propulsion unit that includes a power source, a propeller, a shift position switching mechanism, a control device, and a retention switch. The propeller is driven by the power source to generate propulsive force. The shift position switching mechanism has an input shaft connected to a side of the power source, an output shaft connected to a side of the propeller, and clutches that change a connection state between the input shaft and the output shaft. A shift position of the shift position switching mechanism is switched among forward, neutral, and reverse by engaging and disengaging the clutches. The control device adjusts an engagement force of the clutches. The retention switch is connected to the control device. When the retention switch is turned on by an operator, the control device controls the engagement force of the clutches to retain a hull in a predefined position. The boat propulsion unit provides a boat propulsion unit that can accurately retain a boat at a fixed point.
U.S. Pat. No. 8,317,556 discloses a boat propulsion system that includes a power source, a propulsion section, a shift position switching mechanism arranged to switch among a first shift position, a second shift position, and a neutral position, a gear ratio switching mechanism, an actuator, and a control section. When switching is to be performed from the neutral position to the first shift position and the high-speed gear ratio, the control section is arranged to cause the actuator to, maintain the low-speed gear ratio, switch to the first shift position, and then establish the high-speed gear ratio when the current gear ratio of the gear ratio switching mechanism is the low-speed gear ratio, and cause the actuator to establish the low-speed gear ratio before switching to the first shift position, switch to the first shift position, and then establish the high-speed gear ratio when the current gear ratio of the gear ratio switching mechanism is the high-speed gear ratio. This arrangement improves the durability of a power source and a power transmission mechanism in a boat propulsion system including an electronically controlled shift mechanism.